To prepare your walls for painting:
• Plaster walls—open cracks to a “V” shape and apply plaster. Mesh-tape the area and follow with three coats of joint compound.
• Sheetrock—use mesh tape to cover cracks, apply several coats of joint compound, and sand until smooth.
• Trim/windows/doors—fill all openings with caulk to ensure there are no gaps or holes.
Follow these guidelines for a beautiful, smooth finish every time.
Wilber’s Home Improvement